Electrical resistors are used in combination with capacitors to reduce the electrical charge on a capacitor after the capacitor is disconnected from its circuit. Specifications usually require that the charge be reduced to a safe value within a predetermined period of time. It has been a prior practice to connect a resistor element of a predetermined value between the electrodes of a capacitor. In a capacitor which is contained in a case and filled with a dielectric fluid a resistor element may be utilized inside of the can and between the capacitor leads. One example of this combination is disclosed and described in U.S. Pat. No. 3,302,081-Grahame, assigned to the same assignee as the present invention.
In a capacitor roll section made up of alternate strips of electrode foil and dielectric material, a resistor element may be made up of a carbon loaded paper and inserted into the capacitor roll to contact each foil, at the end of the roll. One example of such a resistor is disclosed and claimed in U.S. Pat. No. 3,840,787-Grahame, assigned to the same assignee as the present invention.
It is difficult to incorporate a resistor in a dry metallized capacitor such as disclosed and described in U.S. Pat. No. 4,037,298-Flanagan, assigned to the same assignee as the present invention. In the Flanagan patent a capacitor roll section is made up of strips of a synthetic resin dielectric, such as polypropylene, on one side of which a very thin metal layer of aluminum, for example, is vapor deposited. These strips are wound together very tightly in a round roll form and may then be used in dry form, i.e., unimpregnated with a dielectric fluid, and perhaps merely encased in a plastic jacket, or, impregnated with a fluid in the usual manner. Automated manufacture of these capacitors make it uneconomical to connect a separate resistor between the electrode leads of the capacitor, and the difficulties of providing an electrical connection between the resistor and the metallized layers also make the insertion of a carbon loaded paper or other electrode interconnection means less desirable.